T Score Conversion Calculator

Work out t score conversion instantly with clear inputs, formula shown and shareable results.

About T Score Conversion Calculator

T scores set the mean at 50 and the standard deviation at 10, so T = 50 + 10z. A z of 1.5 is a T of 65, the 93.3rd percentile - the conventional borderline clinical threshold on instruments like the MMPI and the Child Behaviour Checklist, where T of 70 (two standard deviations) marks clinical significance.

Formulas

z to T

T = 50 + 10z

T to z

z = (T - 50) / 10

Worked example

With the default values below, T Score Conversion Calculator returns Converted Score of 65.000. Change any input above and every figure here is recalculated in your browser.

Inputs used

z score: 1.5
Convertone of z score to T score, T score to z score: z score to T score

Results

Converted Score: 65.000
Underlying z Score: 1.5000
Percentile Rank: 93.32%
Clinical Interpretation: T of 65-69 - borderline elevation

Step by step

1Values used
2z to T
3T to z
4Converted Score= 65.000
5Underlying z Score= 1.5000
6Percentile Rank= 93.32
7Clinical Interpretation= T of 65-69 - borderline elevation

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why are 65 and 70 the clinical cut-offs?

They correspond to 1.5 and 2 standard deviations, the 93rd and 98th percentiles - conventional thresholds for borderline and clinically significant.

Are T scores always mean 50 SD 10?

By definition yes. Do not confuse them with Student's t statistic, which is an entirely different quantity.